On Wed, 2 Jul 2025 at 17:31, Eric Auger <eric.au...@redhat.com> wrote:
>
> From: Haibo Xu <haibo...@linaro.org>
>
> KVM_CAP_ARM_EL2 must be supported by the cpu to enable ARM_FEATURE_EL2.
> In case the host does support NV, expose the feature.
>
> Signed-off-by: Haibo Xu <haibo...@linaro.org>
> Signed-off-by: Miguel Luis <miguel.l...@oracle.com>
> Signed-off-by: Eric Auger <eric.au...@redhat.com>
> Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
>
> ---
> v2 -> v3:
> - check pmu->has_el2 on kvm_arch_init_vcpu() when setting
> KVM_ARM_VCPU_HAS_EL2 feature (Peter)
>
> v1 -> v2:
> - remove isar_feature_aa64_aa32_el2 modif in target/arm/cpu.h
> [Richard] and use el2_supported in kvm_arch_init_vcpu
> ---
> target/arm/kvm.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/target/arm/kvm.c b/target/arm/kvm.c
> index e5708e54ae..46e5f19637 100644
> --- a/target/arm/kvm.c
> +++ b/target/arm/kvm.c
> @@ -250,6 +250,7 @@ static bool
> kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
> */
> int fdarray[3];
> bool sve_supported;
> + bool el2_supported;
> bool pmu_supported = false;
> uint64_t features = 0;
> int err;
> @@ -269,6 +270,14 @@ static bool
> kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
> init.features[0] |= 1 << KVM_ARM_VCPU_SVE;
> }
>
> + /*
> + * Ask for EL2 if supported.
> + */
> + el2_supported = kvm_arm_el2_supported();
> + if (el2_supported) {
> + init.features[0] |= 1 << KVM_ARM_VCPU_HAS_EL2;
> + }
> +
> /*
> * Ask for Pointer Authentication if supported, so that we get
> * the unsanitized field values for AA64ISAR1_EL1.
> @@ -422,6 +431,10 @@ static bool
> kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
> features |= 1ULL << ARM_FEATURE_AARCH64;
> features |= 1ULL << ARM_FEATURE_GENERIC_TIMER;
>
> + if (el2_supported) {
> + features |= 1ULL << ARM_FEATURE_EL2;
> + }
> +
> ahcf->features = features;
>
> return true;
> @@ -1887,6 +1900,9 @@ int kvm_arch_init_vcpu(CPUState *cs)
> cpu->kvm_init_features[0] |= (1 << KVM_ARM_VCPU_PTRAUTH_ADDRESS |
> 1 << KVM_ARM_VCPU_PTRAUTH_GENERIC);
> }
> + if (cpu->has_el2 && kvm_arm_el2_supported()) {
> + cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_HAS_EL2;
> + }
>
> /* Do KVM_ARM_VCPU_INIT ioctl */
> ret = kvm_arm_vcpu_init(cpu);
> --
How does this interact with creating an aarch32 VM with
"-cpu host,aarch64=off" ? Looking at the kernel, it will
fail vcpu_init if you ask for a vcpu with both EL1_32BIT
and HAS_EL2. I guess since the virt board will only request
HAS_EL2 if you say virtualization=on this is fine. Do we
give a sensible error message if the user tries
-accel kvm -M virt,virtualization=on -cpu host,aarch64=off ?
-- PMM
